Weather was not considered to have been a factor in this occurrence. The Abbotsford tower controller cleared C-FCFZ through the control zone southeastbound, but this route was unusual and rarely used. However, there was no requirement to direct overflights away from the airport, and no potential conflict with other traffic was apparent to the tower controller at the time. At the time he instructed the two aircraft to contact Victoria terminal, the tower controller did not recognize a potential conflict between C-FCFZ flying VFR through the control zone at 2500feetasl and C-FHDP climbing to 3000feetasl while conducting a missed approach under IFR. He did not take any action with respect to C-FCFZ. Had the Abbotsford tower controller, once he recognized the impending conflict, employed a more aggressive tactic to alert the Victoria terminal controller, the conflict would likely have been resolved before immediate evasive action was necessary. When the tower controller cleared C-FCFZ to Victoria terminal frequency, he believed C-FCFZ would climb above 2500feetasl and thus leave the Abbotsford control zone, but this did not happen. No communication took place between Abbotsford tower and Victoria terminal regarding C-FCFZ. Consequently, although C-FCFZ had been changed over to Victoria terminal and was no longer in communication with Abbotsford tower, the tower still retained responsibility for C-FCFZ because: C-FCFZ was still in the Abbotsford control zone; C-FCFZ had not been advised that radar services had been terminated; and no coordination/handover from Abbotsford tower to Victoria terminal had taken place. When C-FHDP began the missed approach for Runway07 after a low approach to Runway01, and the tower controller instructed the pilot to contact Victoria terminal frequency, both aircraft were flying in ClassD airspace. The ATC service requirements to be provided to aircraft flying in ClassD airspace had not been met because: no traffic information had been passed to either aircraft; no prior coordination had been made with Victoria terminal with respect to C-FCFZ; and conflict resolution was not provided. The Victoria terminal controller did not detect the conflict until the last moment. The reason for this may have been that C-FCFZ's radar return was displayed on his RSiT as a digital target with mode C altitude. No registration or speed was shown with the aircraft target. This made C-FCFZ's target less conspicuous than aircraft targets associated with jurisdictional data tags. Due to the local practice that discouraged Abbotsford tower controllers from coordinating VFR aircraft with Victoria terminal before a communication transfer, the Victoria terminal controller was not aware of C-FCFZ. As well, the Victoria terminal controller did not hear two calls from C-FCFZ attempting to establish radio contact. These two factors combined likely contributed to the terminal controller not seeing the conflict immediately after C-FHDP contacted him on the missed approach. The timely intervention by the Victoria terminal controller immediately on seeing the conflict was effective.Analysis Weather was not considered to have been a factor in this occurrence. The Abbotsford tower controller cleared C-FCFZ through the control zone southeastbound, but this route was unusual and rarely used. However, there was no requirement to direct overflights away from the airport, and no potential conflict with other traffic was apparent to the tower controller at the time. At the time he instructed the two aircraft to contact Victoria terminal, the tower controller did not recognize a potential conflict between C-FCFZ flying VFR through the control zone at 2500feetasl and C-FHDP climbing to 3000feetasl while conducting a missed approach under IFR. He did not take any action with respect to C-FCFZ. Had the Abbotsford tower controller, once he recognized the impending conflict, employed a more aggressive tactic to alert the Victoria terminal controller, the conflict would likely have been resolved before immediate evasive action was necessary. When the tower controller cleared C-FCFZ to Victoria terminal frequency, he believed C-FCFZ would climb above 2500feetasl and thus leave the Abbotsford control zone, but this did not happen. No communication took place between Abbotsford tower and Victoria terminal regarding C-FCFZ. Consequently, although C-FCFZ had been changed over to Victoria terminal and was no longer in communication with Abbotsford tower, the tower still retained responsibility for C-FCFZ because: C-FCFZ was still in the Abbotsford control zone; C-FCFZ had not been advised that radar services had been terminated; and no coordination/handover from Abbotsford tower to Victoria terminal had taken place. When C-FHDP began the missed approach for Runway07 after a low approach to Runway01, and the tower controller instructed the pilot to contact Victoria terminal frequency, both aircraft were flying in ClassD airspace. The ATC service requirements to be provided to aircraft flying in ClassD airspace had not been met because: no traffic information had been passed to either aircraft; no prior coordination had been made with Victoria terminal with respect to C-FCFZ; and conflict resolution was not provided. The Victoria terminal controller did not detect the conflict until the last moment. The reason for this may have been that C-FCFZ's radar return was displayed on his RSiT as a digital target with mode C altitude. No registration or speed was shown with the aircraft target. This made C-FCFZ's target less conspicuous than aircraft targets associated with jurisdictional data tags. Due to the local practice that discouraged Abbotsford tower controllers from coordinating VFR aircraft with Victoria terminal before a communication transfer, the Victoria terminal controller was not aware of C-FCFZ. As well, the Victoria terminal controller did not hear two calls from C-FCFZ attempting to establish radio contact. These two factors combined likely contributed to the terminal controller not seeing the conflict immediately after C-FHDP contacted him on the missed approach. The timely intervention by the Victoria terminal controller immediately on seeing the conflict was effective. The Abbotsford tower controller released the visual flight rules (VFR) aircraft, C-FCFZ, transiting the control zone, and the instrument flight rules (IFR) aircraft, C-FHDP, conducting a missed approach at the Abbotsford Airport, from his frequency without having a plan in place to ensure their flight paths did not conflict. No traffic information was passed to either aircraft by the Abbotsford tower controller, as is a requirement in Class D airspace. This reduced the likelihood of one aircraft detecting the other, and increased the possibility of a mid-air collision. C-FCFZ did not climb above 2500feet above sea level (asl) as the tower controller expected. As a result, the aircraft remained in the control zone and was the responsibility of the Abbotsford tower controller. When the Abbotsford tower controller became aware that a conflict was imminent, he was unable to contact either aircraft because both were on Victoria terminal frequency. He did not take aggressive action to contact the Victoria terminal controller to safely resolve the conflict. Due to local practices, no handover of C-FCFZ from the Abbotsford tower controller to the Victoria terminal controller occurred. As a result, the Victoria terminal controller was unaware of the presence of C-FCFZ, and did not notice the traffic conflict this posed until the two aircraft were very close, both laterally and vertically.Findings as to Causes and Contributing Factors The Abbotsford tower controller released the visual flight rules (VFR) aircraft, C-FCFZ, transiting the control zone, and the instrument flight rules (IFR) aircraft, C-FHDP, conducting a missed approach at the Abbotsford Airport, from his frequency without having a plan in place to ensure their flight paths did not conflict. No traffic information was passed to either aircraft by the Abbotsford tower controller, as is a requirement in Class D airspace. This reduced the likelihood of one aircraft detecting the other, and increased the possibility of a mid-air collision. C-FCFZ did not climb above 2500feet above sea level (asl) as the tower controller expected. As a result, the aircraft remained in the control zone and was the responsibility of the Abbotsford tower controller. When the Abbotsford tower controller became aware that a conflict was imminent, he was unable to contact either aircraft because both were on Victoria terminal frequency. He did not take aggressive action to contact the Victoria terminal controller to safely resolve the conflict. Due to local practices, no handover of C-FCFZ from the Abbotsford tower controller to the Victoria terminal controller occurred. As a result, the Victoria terminal controller was unaware of the presence of C-FCFZ, and did not notice the traffic conflict this posed until the two aircraft were very close, both laterally and vertically. A local practice discouraged Abbotsford tower controllers from coordinating VFR aircraft with Victoria terminal before a communication transfer coming into effect, in conflict with Section138.1 of NAV CANADA's Air Traffic Control Manual of Operations (ATCMANOPS). This practice, while reducing frequency congestion and workload, increased the risk of a lack of coordination between air traffic control units. C-FCFZ's radar return showed as a digital target with a data tag displaying only altitude, making the target less conspicuous than targets associated with a jurisdictional data tag (registration, altitude, speed, etc.). Without coordination before a communication transfer, the receiving controller may not, therefore, see or perceive aircraft targets not displaying full jurisdictional data tags and may miss a potential conflict.Findings as to Risk A local practice discouraged Abbotsford tower controllers from coordinating VFR aircraft with Victoria terminal before a communication transfer coming into effect, in conflict with Section138.1 of NAV CANADA's Air Traffic Control Manual of Operations (ATCMANOPS). This practice, while reducing frequency congestion and workload, increased the risk of a lack of coordination between air traffic control units. C-FCFZ's radar return showed as a digital target with a data tag displaying only altitude, making the target less conspicuous than targets associated with a jurisdictional data tag (registration, altitude, speed, etc.). Without coordination before a communication transfer, the receiving controller may not, therefore, see or perceive aircraft targets not displaying full jurisdictional data tags and may miss a potential conflict. NAV CANADA amended its document Arrangement between the Vancouver area control centre and the Abbotsford control tower, effective 01September2005. Operations Bulletin05-10 was also issued by Abbotsford tower. In summarizing the pertinent changes, the Bulletin states that these changes are intended "to clearly indicate that prior co-ordination with terminal is required (or) positive control action is to be taken to ensure VFR aircraft being provided service by Abbotsford Tower do not conflict with IFR aircraft activity."Safety Action Taken NAV CANADA amended its document Arrangement between the Vancouver area control centre and the Abbotsford control tower, effective 01September2005. Operations Bulletin05-10 was also issued by Abbotsford tower. In summarizing the pertinent changes, the Bulletin states that these changes are intended "to clearly indicate that prior co-ordination with terminal is required (or) positive control action is to be taken to ensure VFR aircraft being provided service by Abbotsford Tower do not conflict with IFR aircraft activity."